Low voltage electrical connector



Jan. 25, 1966 MCDONALD 3,231,731

LOW VOLTAGE ELECTRICAL CONNECTOR Filed Aug. 30, 1963 2 Sheets-Sheet 1INVENTOR. fiEAM/K C McflOA/ALO Z 16 i ZMZZ WA ATTOPA/EK Jan. 25, 1966MCDONALD 3,231,731

LOW VOLTAGE ELECTRICAL CONNECTOR Filed Aug. 30, 1965 2 Sheets-Sheet 2INVENTOR. FPA/VK C. MCDONALD ATTOPA/EX United States Patent O 3,231,731LOW VOLTAGE ELECTRICAL CONNECTOR Frank D. McDonald, Los Angeles, Calif.,assignor, by

mesne assignments, to American Machine & Foundry Company, New York,N.Y., a corporation of New Jersey Filed Aug. 30, 1963, Ser. No. 305,7536 Claims. (Cl. 2403) This invention relates to low voltage outsidelighting fixtures which are used for lighting some objects, such asbuildings, signs, and various merchandise when it is on public exhibit.Lighting fixtures of the above type are also used now quite extensivelyfor external artificial lighting of homes and gardens between sunset andbedtime for producing various lighting effects.

There are two types of lighting fixtures of the above type now in use:high voltage fixtures using 110 volts, and low voltage fixtures whichuse voltage in the order of 12 volts, corresponding to the 12 voltsystem used in automobiles. In this manner automobile headlights, withminor modifications, can be used as light bulbs. Thus, this inventionrelates to the low voltage fixtures.

The invention is particularly concerned with the means for connectingsuch low voltage electric light bulbs to electric conductors bringinglow voltage electric power to such light bulbs.

It is an object of this invention to provide a low voltage lightingfixture in which a low voltage cord is connectable to a lighting fixtureand a light bulb by means of a cord locking clamp and connector havingtwo projecting barbs which penetrate the insulation of the twowire cordand thus connect the electric bulb to the two multi-strand wires of thecord.

Referring to the drawings:

FIGURE 1 is a perspective view of the low voltage lighting system;

FIGURE 2 is a rear perspective View of a lighting fixture connected toan electric cord;

FIGURE 3 is a side view, partly in section, of the lighting fixtureillustrated in FIG. 2;

FIGURE 4 is a transverse section, taken along line 44, FIG. 3, of thebase of the lighting fixture;

FIGURE 5 is an enlarged perspective view; partly in section, of the baseand of strip terminals and a portion of a clamp connector;

FIGURE 6 is a perspective view of the upper portion of the base, of thecord and of the clamp connector;

FIGURE 7 is a perspective view of a strip terminal;

FIGURE 8 is a side view, partly in section of an alternative form ofconnection between a light bulb and the base of the lighting fixture.

Referring to FIG. 1, it illustrates a perspective view of the lowvoltage lighting system. It includes a two conductor electric plug 10connected to a two conductor cor-d 11 connected to a step-downtransformer 12. The primary of this transformer is connected to the twoconductors of cord 11 and the secondary of the transformer is connectedto an outgoing low voltage two-conductor cord 14. Because of the lowvoltage, the cord and the 201, illustrated in FIG. 2. A plurality oflighting fixtures 16, 17 and 18 is connected to cord 14 in the mannerwhich will be described more in detail below. Plug 10 and cord 11 isconnected to an alternating voltage in the order of 110 to 125 volts.The step-down transformer 12 then steps down this voltage to a voltagein the order of 12 volts, and this low voltage is then impressed on cord14. Because of the low voltage, the cords and the lighting fixturesoffer less electrical hazard than the higher voltage lighting systems,and they also enable one to man- 3,231,731 Patented Jan. 25, 1966ufacture lighting fixtures and connectors which are simpler and cheaperto manufacture than the higher voltage fixtures and connectors. Becauseof the low voltage impressed on cord 14, it also becomes possiblerepeatedly to shift the position of lights 16, 17 and 18 along thelength of the cord to change their location whenever this is necessary.Although a clamp connector used for connecting the fixtures to the cordis provided with two barbs 703 and 704, FIG. 5, for penetrating theinsulation of cord 14, and even though such penetration of theinsulation makes small, permanent open holes in the elastomericinsulation layer, such holes do not present any electrical hazardbecause only very low voltage is impressed on cord 14. For this reasoncord 14 can be used for a considerable length of time, even though thelighting fixtures 16-18 are shifted from place to place along the lengthof cord 14, thus leaving a large number of tiny holes in the elastomericinsulation of this cord.

Referring now to FIG, 2, it illustrates the overall perspe'ctive view ofthe lighting fixtures. The fixture is mounted on a stanchion 202 whichis connected through a bolt or screw 205 to a clevis 204. Clevis 204 isan integral part of a housing 210 accommodating a light bulb 206, a lens207, a ring 208 and a rubber washer 209 which provides a water-tightseal between housing 210 and lens 207. The light bulb 206 is providedwith two outgoing L-shaped prongs 300 and 301, FIG. 3, which are weldedto the conductors 302 and 303 supported by glass bosses 304 and 30Sconstituting an integral part of the hyperbolic glass reflector of thelight bulb. The light bulb is also provided with conventional rods 306and 307 for supporting a tungsten filament 309. Prongs 300 and 301 makean electrical connection with terminal strips 310 and 311 which furnishelectrical power to the light bulb with the aid of a clamp connector312, which is illustrated in FIGS. 2, 3 and 6. Terminal strips 310 and311, one of which is shown more clearly in FIG. 7, are provided withlocking dogs 700, an outwardly flaring, or bent, portion 701, abent-over connector portion 702 and a barb 703 which makes contact withthe multistrand Wire 200 or 201 of cord 14 in the manner which will bedescribed below. The base 500, FIG. 5, is provided with a box-likemember 501 which is used for rigidly mounting the terminal strips 310and 311 in the base 500 in the manner illustrated in FIG. 5. The lockingdogs 700 engage the cross bars 502 and 503 which constitute a part ofthe box member 501. The base 500 is provided with slots 504 and 505through which the terminal strips 310 and 311 are introduced into thebase 500. When the strips 310 and 311 are slid into the base 500, thelocking dogs 700 snap into their outward position after the terminalstrips 310 and 311 are inserted to that position at which the bent-overportion 702 engages the circular portion 506 of the base, The lockingdogs then snap into their locking position after they pass beyond theedges of the cross bars 502 and 503, and in this manner, the terminalstrips are held in the locked position within the base.

In order to provide positive electrical connection between prongs 300and 301 and the terminal strips 310 and 311, base 500 is also providedwith rigid plates 507 and 508 which comprise the extensions of the walls509 and 510 of box 501. To rigidize still further the plates 507 and508, the base is also provided with triangularlyshaped struts 511 and512. In this manner plates 507 and 508 offer very positive supports forprongs 300 and 301 and they guide prongs 300 and 301 into a positive,upper contact with the terminal strips 310 and 3-11. The upper portionsof the rigid plates 507 and 508 are slightly curved outwardly so as toact as guiding means to the prongs 300 and 301 of the light bulb 206. Inthis manner a large 3 area, 'low resistance contact is establishedbetween prongs 300 and 301 and the terminal strips 310 and 3.11.

The terminal strips 310 and 311, as illustrated in FIG. 7, are providedwith the bent-over, flat shoulder portions 7 02, and these flat shoulderportions 702, as also illustrated in FIG. 7, are provided with barbs703. The flat shoulder portions 702 rest on the circular portion 506 ofbase 500. As clearly illustrated in FIG. 5, the circular portion 506 ofbase 500 is provided with two connector walls 513 and 514 whichconstitute an integral part of the molded plastic base 500. Theconnector walls 513 and 514 are provided with four lugs 515 and 516 and517 and 518. Lugs '15 and 516 are locking lugs and lugs 517 and 518 arepivot lugs. The locking lugs 515 and 516 are shorter than the pivot lugs517 and 518 so as to enable one to insert and remove a locking clamp 600which locks a cord 14 to base 500 in the manner which is describedbelow. The locking clamp 600 is provided with twofinger pads 601 and602, a flat beam member 603 and a locking slide member 604 which isprovided with slanting shoulders 605 and 606. The locking clamp 600 isalso provided with four ledges 608-, 609, 610 and 611. All of these fourledges 608-611 are dimensionally identical to each other and they act inpairs insofar as their function is concerned. If the 608-609 pair ofledges is used as pivot ledges, then the ledges 610611 are used as thelocking ledges and vice versa. This will become more apparent inthe'light of a more detailed description of FIG. 6.

The operation of the locking slide is illustrated in FIG. 6. Electricalcord 14 is placed on top of the circular portion 506 of base 500 andbetween connector walls 513 and 514, in the manner illustrated in FIG.6.

It now only remains to clamp and then lock cord 14 to base 500. This isaccomplished by exerting suificient pressure on cord 14 and itselastomeric insulation jacket by rotating clamp 600 in order for thebarbs 703 and 704 to penetrate the insulation jacket and make positivecontact with the multi-strand conductors 200 and 201. This isaccomplished by engaging or placing the pivot ledges 608 and 609 underthe pivot lugs 517 and 518 and then swinging or turning the lockingclamp 600 downwardly in the clockwise direction, as viewed in FIG. 6,and as is also illustrated by an arrow 622, until the clamping andlocking ledges 610 and 611 are depressed below the locking lugs 515 and516. This is accomplished by exerting a pressure on the finger pad 602.When pressure is exerted on the finger pad 602, then the wedgeshapedslanting surface 605 of the locking slide 704 exerts pressure oninsulation jacket '620 of cord 14 and eventually presses the insulationof cord 14 against the barbs 703 and 704, with sutficient force so as tomake the barbs 703 and 704 penetrate the insulation 620 and make contactwith multi-strand conductor 200 or 201 of cord 14. In order to place thelocking clamp 600 into the permanently locked position, pressure isexerted on pad 602 in the direction of an arrow622, with the result thatclamp 600 slides in the direction of arrow 624 over the insulation 620of the wire until the locking ledges 610 and 611 slide under the lockinglugs 515 and 516, which completes the connection of the lighting fixtureto cord 14.

FIGUREB illustrates an alternative form of connecting a low voltagelight bulb 800 to a lighting fixture 801. The .only difference thatexists between the prior figures and FIG. 8 resides in the fact that thelight'bulb 800 now has the well known screw-type base 802 which isconnected to the terminal strips 804 and 805. Strip 805 is connected tothe threaded metallic socket insert 802 while terminal strip 804 isconnected to a jumper 806 which includes a central button 807, makingthe connection with the central terminal, not illustrated, of the lightbulb 800. All the remaining elements of the base and of the clampconnector 312 and the strip terminals 310 and 311 are identical to thesimilarly numbered elements of the base illustrated in FIGS. l-th-rough7.

What I claim is:

1. A lighting fixture connectable to and along the length of an electriccord having an insulation sheath and two conductors, said fixtureincluding a single piece molded hemispherically shaped housing merginginto a hollow insulation base having a flat outer end, first and secondconnector walls projecting outwardly from said flat end, said first andsecond connector walls having a pair of pivot lugs at one end and a pairof locking lug-s at the other end of said walls, a pair of metallicbarbs projecting outwardly from said base and located in a channeldefined by said walls, said cord fitting into said channel, and a cordlocking clamp having a first pair of pivot ledges engaging said pivotlugs and a second pair of locking ledges engaging said locking lugs,said pivot lugs being longer than said locking lugs to permit sliding ofsaid pivot ledges through a portion of the lengths of said pivot lugsfor obtaining a locking engagement between said locking ledges and saidlocking lugs by sliding said locking ledges under :said locking lugs,said clamp also having means for clamping said electric cord againstsaid barbs and said base for electrically connecting said barbs to saidconductors, said barbs penetrating through the insulation sheath of saidcord.

2. A lighting fixture as defined in claim 1 which also includes firstand second terminal strips each having an inner portion connecting saidstrip to a prong of a light bulb, a slot in said base accommodating saidstrip, a flat shoulder portion constituting a bent over external portionof said terminal strip, said shoulder portion resting on top of the flatportion of said base and being located within said channel and betweensaid walls, said barb constituting a bent over portion of said shoulderportion of said terminal strip.

3. The lighting fixture as defined in claim 2 in which said basealsoincludes means for guiding and supporting said prong in electricalengagement with said inner portion ofsaid terminal strip.

4. A lighting fixture comprising a single piece molded housing foratrefiector type light bulb, said fixture including a'hemisphericallyshaped housing for accommodating said bulb, a base outwardly projectingfrom said housing, said base including two spaced from each otherconnector walls, said'walls having a pair of pivotlugs at one end and apair of locking lugs at the other end of said walls, a pair of metallicbarbs projecting outwardly from said base and located in the channeldefinedby said walls for connecting said fixture to an electric cord,and a cord locking clamp having first and second pairs of ledgesengaging, respectively, said locking and pivot lugs, said clamp havingmeans for clamping said cord to said base and to said barbs.

5. A lightingfixture connectable to an electric twoconductor cordcomprising a parabolically shaped housing for accommodating a light bulbwith a parabolically shaped reflector, a hollow insulation baseprojecting outwardly from said housing, said base having a box-shapedmember on the .inner side of said base and having first, second, thirdand fourth walls, said first and third walls facing each other andhaving first and second upright rigid plates, respectively, extendingand projecting inwardly into said base, said first and third wallsincluding firstand second slots, respectively, first and second terminalstrips mounted 'in said first and second slots, respectively, saidterminals projecting outwardly through said base as first and secondbarbs, and means for clamping said cord to said base and said barbs inany desired position along the length of said cord.

6. A lighting fixture connectable along the length of a two-conductorelectric cord by clamping said cord to said fixture, said fixtureincluding a housing for a light bulb having two prongs, a baseconstituting an integral rear part of said fixture, the front part ofsaid fixture having a lens, first and second plates inwardly projectingfrom the central portion of said base, first and second terminal stripsmounted, respectively, along said first and second plates within saidbase, said terminal strips comprising two fla-t metallic springspressing on adjacent flat surfaces of the respective plates, said prongsforming a sliding contact with said surfaces and said terminal stripsfor making electrical connection with said cord, said terminal stripsprojecting outwardly from said base as two barbs, and a clamp connectorhaving two connector walls having two pairs of lugs and a locking clamphaving two pairs of ledges for locking said clamp to said connectorwalls thereby clamping said cord to said base and connecting said twobarbs to the respective two conductors of said cord.

References Cited by the Examiner UNITED STATES PATENTS 2,650,948 9/1953Findlay 33999 2,704,832 3/ 1955 Greenbaum 33999 2,717,365 9/1955Greenbaum 339-99 10 NORTON ANSHER, Primary Examiner.

4. A LIGHTING FIXTURE COMPRISING A SINGLE PIECE MOLDED HOUSING FOR AREFLECTOR TYPE LIGHT BULB, SAID FIXTURE INCLUDING A HEMISPHERICALLYSHAPED HOUSING FOR ACCOMMODATING SAID BULB, A BASE OUTWARDLY PROJECTINGFROM SAID HOUSING, SAID BASE INCLUDING TWO SPACED FROM EACH OTHERCONNECTOR WALLS, SAID WALLS HAVING A PAIR OF PIVOT LUGS OF ONE END AND APAIR OF LOCKING LUGS AT THE OTHER END OF SAID WALLS, A PAIR OF METALLICBARBS PROJECTING OUTWARDLY FROM SAID BASE AND LOCATED IN THE CHANNELDEFINED BY SAID WALLS FOR CONNECTING SAID FIXTURE TO AN ELECTRIC CORD,AND A CORD LOCKING CLAMP HAVING FIRST AND SECOND PAIRS OF LEDGESENGAGIG, RESPECTIVELY, SAID LOCKING AND PIVOT LUGS, SAID CLAMP HAVINGMEANS FOR CLAMPING SAID CORD TO SAID BASE AND TO SAID BARBS.